Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. One example routing solution to LLN challenges is a protocol called Routing Protocol for LLNs or “RPL,” which is a distance vector routing protocol that builds a Destination Oriented Directed Acyclic Graph (DODAG, or simply DAG) in addition to a set of features to bound the control traffic, support local (and slow) repair, etc. The RPL architecture provides a flexible method by which each node performs DODAG discovery, construction, and maintenance.
Currently, when a node wishes to join a DAG, it may do so without requiring permission from another node chosen as the entry point into the DAG. That is, the “child” nodes adopt their “parent” nodes without any input from the parent. Though this may not generally cause a problem, when the child node brings a heavy load with it (e.g., 1000 children of its own, or very high traffic volumes, etc.), this autonomy can result in over-subscription and network congestion. For example, assume that a node N has two options for parent nodes, namely P1 and P2. At first, P1 may be selected, such that node N directs orders of its own children with it to the DAG through P1. If node N has children whose orders aggregate with high capacity, direction of this traffic by node N to P1 may cause P1 to become congested, yielding an increase in congestion-related collisions and other congestion-related problems. In fact, once the selection is effected and traffic is routed by node N to P1, P2 may appear to present an improvement relative to P1, causing node N to reassess and to potentially decide to change from P1 to P2. Assuming a switch to P2, the corresponding transition of orders that come with node N may then cause P2 to become congested, and the fact that P1 is relieved of the node N load would then cause P1 to appear to present an improvement relative to P2, potentially leading to a further transition back to P1. Left unchecked, repetition of this phenomenon might continue, resulting in node N traffic flip/flopping between P1 and P2, yielding network instability in addition to undue congestion.